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Table 3. Multivariable regression on the number of successful
compressions on normal-sized manikins using a generalized
linear model
95% CI limits

Chisquare

P value

0.26

1.64

2.66

68.34

<0.001

Variable

Estimate

Ethnicity

2.15

Black

0.59

0.23

0.15

1.04

6.73

0.01

Asian

0.90

0.20

0.50

1.30

19.76

<0.001

White

0.94

0.19

0.56

1.32

23.73

<0.001

Hispanic
Order*
123

-0.21

0.12

-0.44

0.02

3.43

0.06

132

-0.02

0.10

-0.22

0.18

0.03

0.87

213

-0.46

0.12

-0.67

-0.22

14.26

<0.001

231

-0.37

0.12

-0.59

-0.14

10.21

0.001

0.10

-0.20

0.21

0.95

-0.01

23.67

<0.001

312
321

0.006
0

0.003 -0.02

Age

-0.02

BMI

0.02

0.007

0.003

0.03

5.83

0.02

Upper body
strength

0.004

0.001

0.006

8.81

0.003

*The order in which participants performed CPR on the three manikins, where 1 represents a normal manikin; 2, an obese manikin; and 3, a morbidly obese manikin.

As shown in Table 3, age, BMI, upper body strength, ethnicity, and manikin order were all signiﬁcantly associated with
the number of successful compressions. The performance of
black, Asian, and white participants was signiﬁcantly better
than that of Hispanics; an increase in age by 1 year was associated with a decrease in the number of successful compressions
by 0.0167; an increase in BMI by one unit was associated
with an increase in the number of successful compressions by
0.0159; and a one unit increase in upper body strength was
associated with an increase in number of successful compressions by 0.0038.
The order of performing CPR on normal, obese, and morbidly obese manikins was randomized using a randomization table where 1 represented a normal manikin; 2, an obese manikin;
and 3, a morbidly obese manikin. Regarding the randomization
order, the orders 213 and 231 were associated with a lower
number of successful compressions than the order 321, which
was the reference point.
DISCUSSION
High-quality, eﬀective compressions are vital to successful
CPR (9, 12). Results of this study indicate that compression
quality is lower when performed on obese and morbidly obese
adult simulation manikins. Only a few other studies have
explored the relation between obesity and quality CPR. Edelson and associates found that morbid obesity was associated
with poor outcomes in comparison to subjects who were not
morbidly obese (13). They also found that morbidly obese
October 2017

patients received shallower chest compressions. Hamilton
concluded that CPR training for individuals working in a hospital should be representative of potential situations that they
may encounter (14), and it is likely that health care workers
will encounter obese or morbidly obese patients. Implications
for healthcare workers include maintaining competency of
basic life support skills and being prepared to deliver CPR
on obese patients.
A literature search on the impact of rescuer characteristics
such as height, weight, gender, and upper body strength yielded
no results. However, the potential eﬀect of these characteristics should be considered. Our study showed that signiﬁcant
relationships exist between certain demographic and personal
variables and quality of chest compressions.
While our study was limited by its approach of using simulation manikins as a surrogate for obese and morbidly obese
CPR recipients, its results regarding eﬀective CPR on obese
and morbidly obese patients clearly warrant further investigation. One area to investigate is the use of mechanical compression devices and feedback devices that are now available to
assist in administering quality compressions. The prevalence
of survival to discharge after in-hospital CPR in obese and
morbidly obese patients should be studied. Finally, research
is needed to examine outcomes and eﬀectiveness of compressions in combination with rescuer characteristics, with the
aim of increasing quality of compressions among individual
providers. Innovative methods need to be developed to aid
in performing successful CPR on obese and morbidly obese
patients. Otherwise, the mortality rate in this population will
remain at an unacceptable level.
Acknowledgments
This study was supported by a grant from the Cardiovascular
Research Review Committee of Baylor Scott & White Health.
Special thanks to the research team who assisted with this study:
Erin Weaver, BSN, RN, Randy Marcel, MD, Kristi Verschelden,
RN, and Julie Dunagan.
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Table of Contents for the Digital Edition of Baylor University Medical Center Proceedings October 2017